Partial Encryption

i am developing a set of web service methods which return reporting data.
ideally i do not want to use HTTPS due to the extra performance hit. what
would be ideal is to encrypt only that data which is sensitive. for example,
1 particular report has 12 columns of data. but only 1 column of data really
needs to be encrypted over the wire (the client name).
at the moment my web service method returns a dataset. although i can change
this, if it is easier to implement partial encryption by returning a
different type.

please could anyone advise if it is possible to perform partial encryption
in .NET2.0 like this? if so i would be grateful for any advice, URLS, etc.
to get me off on the right foot.

thanks


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